Mediterranean dietary pattern and prediction of all-cause mortality in a US population. Results from the NIH-AARP diet and health study

The authors report that the Mediterranean diet has been suggested to play a beneficial role for health and longevity, but no prospective US study has investigated the Mediterranean dietary pattern in relation to mortality. Study participants included 214,284 men and 166,012 women in the National Institutes of Health (NIH)-AARP (formerly known as the American Association of Retired Persons) Diet and Health Study. During follow up for all-cause mortality (1995-2005), 27,799 deaths were documented. In the first 5 years of follow up, 5,985 cancer deaths and 3,451 cardiovascular disease (CVD) deaths were reported. The investigators used a 9-point score to assess conformity with the Mediterranean dietary pattern (components included vegetables, legumes, fruits, nuts, whole grains, fish, monounsaturated fat saturated fat ratio, alcohol, and meat). They calculated hazard ratios (HRs) and 95% confidence intervals (CIs) using age- and multivariate-adjusted Cox models.

Results showed that the Mediterranean diet was associated with reduced all-cause and cause-specific mortality. In men, the multivariate HRs comparing high to low conformity for all-cause, CVD, and cancer mortality were 0.79 (95% CI, 0.76-0.83), 0.78 (95% CI, 0.69-0.87), and 0.83 (95% CI, 0.76-0.91), respectively. In women, an inverse association was seen with high conformity with this pattern: decreased risks that ranged from 12% for cancer mortality to 20% for all-cause mortality (P=.04 and P<.001, respectively, for the trend). When they restricted their analyses to never smokers, associations were virtually unchanged. The authors conclude that their results provide strong evidence for a beneficial effect of higher conformity with the Mediterranean dietary pattern on risk of death from all causes, including deaths due to CVD and cancer, in a US population.

Comments by R. Curtis Ellison: While a number of recent studies in many countries have shown that subjects who tend to follow a Mediterranean-type diet show reduced risk of most chronic diseases and greater survival, this study is important since it is so large (about 380,000 subjects) and evaluated Americans. It strongly supports the previous studies, and suggests that meeting requirements for at least 6 of the 9 components of this dietary pattern is associated with lower all-cause mortality, cardiovascular disease mortality, and cancer mortality among both men and women.

The scoring system used in this study is based on one published by Fung et al (Am J Clin Nutr 2005;82:163-173) using data from American women in the Nurse’s Health Study. The scoring system is very similar to one reported by Trichopoulou et al (Public Health Nutr 2004;7:943-947), that has been used in most European studies. The alternate (American) version of the Mediterranean diet score differs from that of Trichopoulou et al in that it separates fruit and nuts into two groups, eliminates dairy, includes only whole grains and only red and processed meats, and uses the same alcohol range for both men and women (5-25 g/day, the equivalent of at least about _ of a typical US drink but not more than two drinks). The scoring system for the American version used in the present study is shown below, from Fung et al.